1. Field of the Invention
The present invention relates to communications networks, and more specifically, to a method and system for interfacing a legacy circuit-switched network with a packet-switched network.
2. Description of Related Art
Packet-switched networks, such as the Internet, are increasingly being used to carry traffic, such as voice calls, that have traditionally used circuit-switched networks, such as the public switched telephone network (PSTN). The shift is being motivated by a number of different factors. For example, packet-switched networks may allow voice traffic to be integrated with data, video, and other traffic. Packet-switched networks are typically less expensive to build and maintain than circuit-switched networks. Packet-switched network also often have higher bandwidths than what is available in most circuit-switched networks.
To accommodate voice traffic over packet-switched networks, which is often referred to as voice over Internet Protocol (xe2x80x9cVoIPxe2x80x9d) or Internet telephony, a number of different call processing protocols, i.e., procedures for connecting a calling party to one or more called parties, have been developed. Such call processing protocols include H.323, the Media Gateway Control Protocol (MGCP), Megaco, and the Session Initiation Protocol (SIP).
One challenge with using such call processing protocols is being able to integrate them with legacy circuit-switched networks. This integration is important because packet-switched networks are likely to co-exist with legacy circuit-switched networks for quite some time. One goal of such integration is to provide similar telecommunications services to subscribers, regardless of whether the subscribers are using a legacy circuit-switched network or a packet-switched network. For example, if a subscriber has enhanced telephony services, such as call forwarding, call waiting, and/or call screening, available to him or her on a legacy circuit-switched network, it would be advantageous to make similar enhanced services available to the subscriber when operating on packet-switched networks.
To achieve this, the packet-switched network should have access to: (1) the subscriber""s service profile, which specifies the services to which her or she subscribes and any parameters for the services; and (2) the service logic, which specifies how to provide the service based on the parameters in the service profile. The second requirement may be fulfilled by programming the service logic into one or more servers or other network elements that provide the services in the packet-switched network. Thus, the service logic used to provide a service in a packet-switched network may be different than the service logic used to provide the comparable service in the legacy circuit-switched network. Alternatively, servers in the packet-switched network may execute existing service logic in the legacy circuit-switched network to provide services in the packet-switched network. This may be achieved through the use of intemetwork queries and mediated service logic, such as described in U.S. patent application Ser. No. 09/410,869, filed Oct. 1, 1999, which is fully incorporated herein by reference.
With respect to the first requirement, however, service profile information may be maintained in a database, such as a service control point (SCP) or home location register (HLR), that is part of the legacy circuit-switched network. Thus, it is desirable for the servers or other network elements that execute the service logic in the packet-switched network to have access to the service profile information maintained in the legacy circuit-switched network and to use the service profile information to provide services to subscribers using the packet-switched network.
In a first principal aspect, exemplary embodiments of the present invention provide a method of interfacing a circuit-switched network with a packet-switched network. In accordance with the method, a registration message indicating a subscriber is connected to said packet-switched network is received. In response to this registration message, a request message is sent to a call control system of the circuit-switched network. The request message identifies the subscriber. A response message is received from the call control system. The response message includes service profile information for the subscriber. At least one service parameter derived from the service profile information is stored in a service database of the packet-switched network.
In a second principal aspect, exemplary embodiments of the present invention provide a method of interfacing a legacy network with a Session Initiation Protocol (SIP) network. In accordance with the method, a registration message indicating presence of a subscriber in a SIP network is received. In response to the registration message, a request message is sent to a call control system of said network. The request message identifies the subscriber. A response message is received from the call control system. The response message includes service profile information for the subscriber. At least one service parameter derived from the service profile information is stored in a SIP service database.
In a third principal aspect, exemplary embodiments of the present invention provide a system for interfacing a circuit-switched network that includes a call control system with a packet-switched network. This system comprises an interface engine that sends a request message to a call control system of the circuit-switched network, in response to a registration message. The request message identifies the subscriber, and the registration message indicates a subscriber is connected to the packet-switched network.